The GETALL and SETALL commands in semctl(2) recorded the number of semaphores in the target set, dropped the lock protecting the set, allocated a buffer sized for that count, and reacquired the lock. A sequence-number check was used to verify that the set had not been replaced in the interim, but the sequence number wraps after 0x8000 create/destroy cycles. By rapidly destroying and recreating semaphore sets at the same index, another process can cause the sequence number to wrap, allowing a set with a different number of semaphores to pass validation. The subsequent copy then reads or writes past the end of the allocated buffer. An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://security.freebsd.org/advisories/FreeBSD-SA-26:54.sysvsem.asc Vendor Advisory, Mailing List
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.8 · freebsdNVD modified 2026-10-27 12:10
Affected (CPE criteria) 25
cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p5:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p6:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p7:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p10:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p11:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p9:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.1:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.1:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.1:rc2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.1:rc3-p1:*:*:*:*:*:*
References 1
- https://security.freebsd.org/advisories/FreeBSD-SA-26:54.sysvsem.asc Vendor Advisory, Mailing List